Why was the word "Emperor" or "Empress" not used as much in British/European Monarchies despite the British/various European Empires? EG: King George III declined to use "Emperor of the British Isles", preferring instead "The United Kingdom of Great Britain and Ireland." Why?

by zz2113
khosikulu

There are several old but enlightening comments from /u/WhenTheRvlutionComes, /u/intangible-tangerine, and /u/SheldonNovick in this thread here, but there is always room for further discussion.